Network Selection Methods And Apparatus With Home Network Prioritization After Network Signal Recovery Or Power-On

ABSTRACT

A network selection method for a mobile station which is associated with a Home Public Land Mobile Network (HPLMN) identified by a home Mobile Network Code (MNC) and Mobile Country Code (MCC) pair. The mobile station identifies a plurality of PLMNs in a geographic area, and selects a non-home PLMN identified by a non-home MNC/MCC pair and designated as a Registered PLMN (RPLMN). In response to regaining signal coverage from an out-of-coverage condition with the RPLMN, or being powered-on from a power-off state entered while operating with the RPLMN, the mobile station selects the HPLMN if the HPLMN identified by the home MNC/MCC pair is available. Otherwise, if the HPLMN is unavailable and the RPLMN identified by the non-home MNC/MCC pair is available, the mobile station selects the RPLMN. However, if the RPLMN is unavailable, the mobile station selects an alternate PLMN in accordance with an automatic or manual network selection method.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of and claims priority to aU.S. non-provisional patent application having application Ser. No.10/788,715 and filing date of 27 Feb. 2004, now U.S. Pat. No. “ABC123”,which claims the benefit of U.S. provisional patent application havingapplication Ser. No. 60/519,514 and filing date of 13 Nov. 2003, eachapplication being hereby incorporated by reference herein.

BACKGROUND

1. Field of the Technology

The present application relates generally to mobile stations and networkselection methods employed thereby.

2. Description of the Related Art

A mobile communication device, such as a cellular mobile station, may becapable of making and receiving telephone calls and/or sending andreceiving data over a wireless communication network. Before it is ableto do this, the mobile station selects and registers with one of aplurality of communication networks which are available within itsgeographic coverage area. After registering with the selected network,the mobile station operates in an idle mode where it “camps-on” aparticular wireless communication channel of the network to monitor forcalls or messages. “Network selection” is the particular processperformed by the mobile station for selecting the one communicationnetwork through which to register and operate.

Cellular telephony operation and network selection schemes aredocumented in standards specifications that govern the behavior ofcellular mobile stations and associated systems. One well-known cellularstandard is the Global System for Mobile Communications (GSM) standard.GSM 03.22/European Technical Standards Institute (ETSI) TX 100 930,Technical Specification (TS) 23.122 from the 3^(rd) GenerationPartnership Project (3GPP), and other related standards specificationsdescribe the many details of cellular operation and network selection.These documents describe how a mobile station behaves as it moves androams between various regions and countries to maintain coverage withnetworks (referred to as Public Land Mobile Networks or PLMNs),primarily for the purpose of providing continuous telephone service.

Traditionally, a mobile station performs network selection by initiallyscanning to identify all available communication networks within itssurrounding coverage area. Each network is identified by a unique MobileCountry Code (MCC) and Mobile Network Code (MNC) pair. If the “homenetwork” (HPLMN) of the mobile station is available, the mobile stationwill ordinarily select and operate with the home network. If the HPLMNis unavailable, the mobile station will ordinarily select and operatewith the communication network having the highest priority in apreferred network list stored in memory of the mobile station. There maybe several preferred network lists, commonly referred to as PreferredPLMN lists (PPLMN lists), stored on a Subscriber Identity Module (SIM)card of the mobile station. For example, the PPLMN lists may include auser-controlled PPLMN (U-PPLMN) list and an operator-controlled PLMN(O-PPLMN) list. The above-described network selection method is commonlyreferred to as an “automatic” network selection method. As analternative to this automatic selection method, an end-user of themobile station may be provided with the ability to manually select froma plurality of listed available networks which are visibly displayed onthe mobile device. This conventional network selection method may bereferred to as a “manual” network selection method.

Some issues exist with conventional network selection techniques for amobile station, particularly relating to operation with the HPLMN. Afterrecovering from an out-of-coverage condition, a mobile station operatesto select the PLMN with which it had just previously registered (i.e.its “RPLMN”). If the RPLMN is unavailable, the mobile station performs ascan to identify and select a PLMN which may be the HPLMN. However, thespecifications do not clearly and specifically address the situationwhere the RPLMN is not the HPLMN of the mobile station. If the RPLMN isnot the HPLMN, and the HPLMN is available after the recovery from theout-of-coverage condition, it is specified that the mobile station islimited to selecting the non-home RPLMN (if available) upon recovery.Such conventional operation is described in ETSI specs 3.22/23.122.Similar problems exist when the mobile station is powered off whileoperating with the RPLMN and subsequently powered back on. In a relatedissue, the standards specify that if the last RPLMN is unavailable whilethe mobile station is in “manual” mode, the mobile station shall camp onany network providing emergency service. This selected network may notbe the optimal network with which to operate, especially, for example,if the home network is available.

Accordingly, there is a resulting need for network selection methods andapparatus that overcome the deficiencies of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of present invention will now be described by way of examplewith reference to attached figures, wherein:

FIG. 1 is a block diagram of a communication system which includes amobile station for communicating in a wireless communication network;

FIG. 2 is a more detailed example of a mobile station for use in thewireless communication network;

FIG. 3 is a particular structure of a system for communicating with themobile station;

FIG. 4 is an illustration of a mobile station which is currentlyregistered with and communicating through a non-home communicationnetwork while its home network is made available;

FIG. 5 is a flowchart for describing a method of selecting acommunication network according to current standards;

FIG. 6 is a flowchart for describing a method of “automatic” selectionof a communication network with home network prioritization afternetwork signal recovery and/or power-on; and

FIG. 7 is a flowchart for describing a method of “manual” selection of acommunication network with home network prioritization after networksignal recovery and/or power-on.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Network selection methods and apparatus with home network prioritizationafter network signal recovery and/or power on are described herein. Inone illustrative example involving “automatic” network selection, amobile station selects and operates with a non-home communicationnetwork. The mobile station then experiences an out-of-coveragecondition (or a power down condition) but subsequently regains signalcoverage (or is powered back on). In response, the mobile station scansto identify a plurality of communication networks in its coverage area.If a home communication network (e.g. HPLMN) is identified as beingavailable, the mobile station selects and operates with the homecommunication network. Otherwise, if the previous non-home communicationnetwork (e.g. RPLMN) is identified as being available, the mobilestation continues operation with the previous non-home communicationnetwork. In another illustrative example involving “manual” networkselection, a user input from a user interface for manually selecting acommunication network with which the mobile station will operate isreceived. After regaining network signal coverage from anout-of-coverage condition, or after powering on from a power-off state,the mobile station scans to identify a plurality of communicationnetworks in a coverage area. If the previous manually-selected network(e.g. the RPLMN) is available but the home network is unavailable asidentified by the scanning, then the mobile station continues to operatewith the previous manually-selected network. If a home communicationnetwork (e.g. HPLMN) is identified as being available by the scanning,however, the mobile station causes a visual input prompt to be displayedfor manual selection of the home network.

FIG. 1 is a block diagram of a communication system 100 which includes amobile station 102 which communicates through a wireless communicationnetwork 104. Mobile station 102 preferably includes a visual display112, a keyboard 114, and perhaps one or more auxiliary user interfaces(UI) 116, each of which are coupled to a controller 106. Controller 106is also coupled to radio frequency (RF) transceiver circuitry 108 and anantenna 110.

In most modern communication devices, controller 106 is embodied as acentral processing unit (CPU) which runs operating system software in amemory component (not shown). Controller 106 will normally controloverall operation of mobile device 102, whereas signal processingoperations associated with communication functions are typicallyperformed in RF transceiver circuitry 108. Controller 106 interfaceswith device display 112 to display received information, storedinformation, user inputs, and the like. Keyboard 114, which may be atelephone type keypad or full alphanumeric keyboard, is normallyprovided for entering data for storage in mobile station 102,information for transmission to network 104, a telephone number to placea telephone call, commands to be executed on mobile station 102, andpossibly other or different user inputs.

Mobile station 102 sends communication signals to and receivescommunication signals from network 104 over a wireless link via antenna110. RF transceiver circuitry 108 performs functions similar to those ofbase station 120, including for example modulation/demodulation andpossibly encoding/decoding and encryption/decryption. It is alsocontemplated that RF transceiver circuitry 108 may perform certainfunctions in addition to those performed by base station 120. It will beapparent to those skilled in art that RF transceiver circuitry 108 willbe adapted to particular wireless network or networks in which mobilestation 102 is intended to operate. When mobile station 102 is fullyoperational, an RF transmitter of RF transceiver circuitry 108 istypically keyed or turned on only when it is sending to network, and isotherwise turned off to conserve resources. Such intermittent operationof transmitter has a dramatic effect on power consumption of mobilestation 102. Similarly, an RF receiver of RF transceiver circuitry 108is typically periodically turned off to conserve power until it isneeded to receive signals or information (if at all) during designatedtime periods.

Mobile station 102 includes a battery interface 134 for receiving one ormore rechargeable batteries 132. When mobile station 102 is powered onby the end user (at keyboard 114, for example), battery 132 provideselectrical power to (most if not all) electrical circuitry in mobilestation 102. Battery interface 134 provides for both a mechanical andelectrical connection for battery 132. Battery interface 134 is coupledto a regulator 136 which regulates power for the device. When mobilestation 102 is powered off by the end user to place mobile station 102in a power-off state, electrical power to most circuits (e.g. at last toRF transceiver 108) is cut off.

Mobile station 102 may consist of a single unit, such as a datacommunication device, a cellular telephone, a multiple-functioncommunication device with data and voice communication capabilities, apersonal digital assistant (PDA) enabled for wireless communication, ora computer incorporating an internal modem. Alternatively, mobilestation 102 may be a multiple-module unit comprising a plurality ofseparate components, including but in no way limited to a computer orother device connected to a wireless modem. In particular, for example,in the mobile station block diagram of FIG. 1, RF transceiver circuitry108 and antenna 110 may be implemented as a radio modem unit that may beinserted into a port on a laptop computer. In this case, the laptopcomputer would include display 112, keyboard 114, one or more auxiliaryUIs 116, and controller 106 embodied as the computer's CPU. It is alsocontemplated that a computer or other equipment not normally capable ofwireless communication may be adapted to connect to and effectivelyassume control of RF transceiver circuitry 108 and antenna 110 of asingle-unit device such as one of those described above. Such a mobilestation 102 may have a more particular implementation as described laterin relation to mobile station 200 of FIG. 2.

Mobile station 102 operates using a Subscriber Identity Module (SIM) 140which is connected to or inserted in mobile station 102 at a SIMinterface 142. SIM 140 is one type of a conventional “smart card” usedto identify an end user (or subscriber) of mobile station 102 and topersonalize the device, among other things. Without SIM 140, the mobileterminal is not fully operational for communication through wirelessnetwork 104. By inserting SIM 140 into the mobile terminal, an end usercan have access to any and all of his/her subscribed services. In orderto identify the subscriber, SIM 140 contains some user parameters suchas an International Mobile Subscriber Identity (IMSI) as well as apreferred network list. In addition, SIM 140 is typically protected by afour-digit Personal Identification Number (PIN) which is stored thereinand known only by the end user. An advantage of using SIM 140 is thatend users are not necessarily bound by any single physical mobileterminal. Typically, the only element that personalizes a mobileterminal is a SIM. Therefore, the user can access subscribed servicesusing most any mobile terminal equipped to operate with the user's SIM140. SIM 140 generally includes a processor and memory for storinginformation. SIM 140 and its interfacing standards are well known. Forinterfacing with a standard GSM device having SIM interface 142, aconventional SIM 140 has six (6) connections.

Mobile station 102 communicates in and through wireless communicationnetwork 104. In the embodiment of FIG. 1, wireless network 104 operatesin accordance with a Global Systems for Mobile (GSM) and General PacketRadio Service (GPRS). Wireless network 104 includes a base station 120with an associated antenna tower 118, a Mobile Switching Center (MSC)122, a Home Location Register (HLR) 132, a Serving General Packet RadioService (GPRS) Support Node (SGSN) 126, and a Gateway GPRS Support Node(GGSN) 128. MSC 122 is coupled to base station 120 and to a landlinenetwork, such as a Public Switched Telephone Network (PSTN) 124. SGSN126 is coupled to base station 120 and to GGSN 128, which is in turncoupled to a public or private data network 130 (such as the Internet).HLR 132 is coupled to MSC 122 and SGSN 126.

Base station 120, including its associated controller and antenna tower118, provides wireless network coverage for a particular coverage areacommonly referred to as a “cell”. Base station 120 transmitscommunication signals to and receives communication signals from mobilestations within its cell via antenna tower 118. Base station 120normally performs such functions as modulation and possibly encodingand/or encryption of signals to be transmitted to mobile station 102 inaccordance with particular, usually predetermined, communicationprotocols and parameters, under control of its controller. Base station120 similarly demodulates and possibly decodes and decrypts, ifnecessary, any communication signals received from mobile station 102within its cell. Communication protocols and parameters may vary betweendifferent networks. For example, one network may employ a differentmodulation scheme and operate at different frequencies than othernetworks.

The wireless link shown in communication system 100 of FIG. 1 representsone or more different channels, typically different radio frequency (RF)channels, and associated protocols used between wireless network 104 andmobile station 102. An RF channel is a limited resource that must beconserved, typically due to limits in overall bandwidth and a limitedbattery power of mobile station 102. Those skilled in art willappreciate that a wireless network in actual practice may includehundreds of cells, each served by a distinct base station 120 andtransceiver, depending upon desired overall expanse of network coverage.All base station controllers and base stations may be connected bymultiple switches and routers (not shown), controlled by multiplenetwork controllers.

For all mobile station's 102 registered with a network operator,permanent data (such as a user's profile of mobile station 102) as wellas temporary data (such as a current location of mobile station 102) arestored in HLR 132. In case of a voice call to mobile station 102, HLR132 is queried to determine the current location of mobile station 102.A Visitor Location Register (VLR) of MSC 122 is responsible for a groupof location areas and stores the data of those mobile stations that arecurrently in its area of responsibility. This includes parts of thepermanent mobile station data that have been transmitted from HLR 132 tothe VLR for faster access. However, the VLR of MSC 122 may also assignand store local data, such as temporary identifications. Optionally, theVLR of MSC 122 can be enhanced for more efficient co-ordination of GPRSand non-GPRS services and functionality (e.g. paging forcircuit-switched calls which can be performed more efficiently via SGSN126, and combined GPRS and non-GPRS location updates).

Being part of the GPRS network, Serving GPRS Support Node (SGSN) 126 isat the same hierarchical level as MSC 122 and keeps track of theindividual locations of mobile stations. SGSN 126 also performs securityfunctions and access control. Gateway GPRS Support Node (GGSN) 128provides interworking with external packet-switched networks and isconnected with SGSNs (such as SGSN 126) via an IP-based GPRS backbonenetwork. SGSN 126 performs authentication and cipher setting proceduresbased on the same algorithms, keys, and criteria as in existing GSM. Inconventional operation, cell selection may be performed autonomously bymobile station 102 or by base station 120 instructing mobile station 102to select a particular cell. Mobile station 102 informs wireless network104 when it reselects another cell or group of cells, known as a routingarea.

In order to access GPRS services, mobile station 102 first makes itspresence known to wireless network 104 by performing what is known as aGPRS “attach”. This operation establishes a logical link between mobilestation 102 and SGSN 126 and makes mobile station 102 available toreceive, for example, pages via SGSN, notifications of incoming GPRSdata, or SMS messages over GPRS. In order to send and receive GPRS data,mobile station 102 assists in activating the packet data address that itwants to use. This operation makes mobile station 102 known to GGSN 128;interworking with external data networks can thereafter commence. Userdata may be transferred transparently between mobile station 102 and theexternal data networks using, for example, encapsulation and tunneling.Data packets are equipped with GPRS-specific protocol information andtransferred between mobile station 102 and GGSN 128.

As apparent from the above, the wireless network includes fixed networkcomponents including RF transceivers, amplifiers, base stationcontrollers, network servers, and servers connected to network. Thoseskilled in art will appreciate that a wireless network may be connectedto other systems, possibly including other networks, not explicitlyshown in FIG. 1. A network will normally be transmitting at very leastsome sort of paging and system information on an ongoing basis, even ifthere is no actual packet data exchanged. Although the network consistsof many parts, these parts all work together to result in certainbehaviours at the wireless link.

FIG. 2 is a detailed block diagram of a preferred mobile communicationdevice, a mobile station 200. Mobile station 200 is preferably a two-waycommunication device having voice and data communication capabilities,including the capability to communicate with other computer systems.Depending on the functionality provided by mobile station 200, it may bereferred to as a data messaging device, a two-way pager, a cellulartelephone with data messaging capabilities, a wireless Internetappliance, or a data communication device (with or without telephonycapabilities).

If mobile station 200 is enabled for two-way communication, it willnormally incorporate a communication subsystem 211, which includes areceiver 212, a transmitter 214, and associated components, such as oneor more (preferably embedded or internal) antenna elements 216 and 218,local oscillators (LOs) 213, and a processing module such as a digitalsignal processor (DSP) 220. Communication subsystem 211 is analogous toRF transceiver circuitry 108 and antenna 110 shown in FIG. 1. As will beapparent to those skilled in field of communications, particular designof communication subsystem 211 depends on the communication network inwhich mobile station 200 is intended to operate.

Network access requirements will also vary depending upon type ofnetwork utilized. In GPRS networks, for example, network access isassociated with a subscriber or user of mobile station 200. A GPRSdevice therefore requires a Subscriber Identity Module, commonlyreferred to as a “SIM” 262, in order to operate on the GPRS network.Without such a SIM 262 inserted in a SIM interface 264, a GPRS devicewill not be fully functional. Local or non-network communicationfunctions (if any) may be operable, but mobile station 200 will beunable to carry out any functions involving communications over thenetwork. SIM 262 includes those features described in relation to FIG.1.

Mobile station 200 will operate in connection with one of a plurality ofbase stations 202 associated with the same or different networks at anygiven time. Mobile station 200 may send and receive communicationsignals with the selected network after required network registration oractivation procedures have been completed. Network selection of thepresent application is described in relation to FIGS. 6-7 below. Signalsreceived by antenna 216 through the network are input to receiver 212,which may perform such common receiver functions as signalamplification, frequency down conversion, filtering, channel selection,and like, and in example shown in FIG. 2, analog-to-digital (A/D)conversion. A/D conversion of a received signal allows more complexcommunication functions such as demodulation and decoding to beperformed in DSP 220. In a similar manner, signals to be transmitted areprocessed, including modulation and encoding, for example, by DSP 220.These DSP-processed signals are input to transmitter 214 fordigital-to-analog (D/A) conversion, frequency up conversion, filtering,amplification and transmission over communication network via antenna218. DSP 220 not only processes communication signals, but also providesfor receiver and transmitter control. For example, the gains applied tocommunication signals in receiver 212 and transmitter 214 may beadaptively controlled through automatic gain control algorithmsimplemented in DSP 220.

Mobile station 200 includes a microprocessor 238 (which is oneimplementation of controller 106 of FIG. 1) which controls overalloperation of mobile station 200. Communication functions, including atleast data and voice communications, are performed through communicationsubsystem 211. Microprocessor 238 also interacts with additional devicesubsystems such as a display 222, a flash memory 224, a random accessmemory (RAM) 226, auxiliary input/output (I/O) subsystems 228, a serialport 230, a keyboard 232, a speaker 234, a microphone 236, a short-rangecommunications subsystem 240, and any other device subsystems generallydesignated at 242. Data and control lines 260 extend between SIMinterface 254 and microprocessor 238 for communicating data therebetweenand for control. Some of the subsystems shown in FIG. 2 performcommunication-related functions, whereas other subsystems may provide“resident” or on-device functions. Notably, some subsystems, such askeyboard 232 and display 222, for example, may be used for bothcommunication-related functions, such as entering a text message fortransmission over a communication network, and device-resident functionssuch as a calculator or task list. Operating system software used bymicroprocessor 238 is preferably stored in a persistent store such asflash memory 224, which may alternatively be a read-only memory (ROM) orsimilar storage element (not shown). Those skilled in the art willappreciate that the operating system, specific device applications, orparts thereof, may be temporarily loaded into a volatile store such asRAM 226.

Microprocessor 238, in addition to its operating system functions,preferably enables execution of software applications on mobile station200. A predetermined set of applications which control basic deviceoperations, including at least data and voice communication applications(such as a network selection scheme), will normally be installed onmobile station 200 during its manufacture. A preferred application thatmay be loaded onto mobile station 200 may be a personal informationmanager (PIM) application having the ability to organize and manage dataitems relating to user such as, but not limited to, e-mail, calendarevents, voice mails, appointments, and task items. Naturally, one ormore memory stores are available on mobile station 200 and SIM 262 tofacilitate storage of PIM data items and other information.

The PIM application preferably has the ability to send and receive dataitems via the wireless network. In a preferred embodiment, PIM dataitems are seamlessly integrated, synchronized, and updated via thewireless network, with the mobile device user's corresponding data itemsstored and/or associated with a host computer system thereby creating amirrored host computer on mobile station 200 with respect to such items.This is especially advantageous where the host computer system is themobile device user's office computer system. Additional applications mayalso be loaded onto mobile station 200 through network, an auxiliary I/Osubsystem 228, serial port 230, short-range communications subsystem240, or any other suitable subsystem 242, and installed by a user in RAM226 or preferably a non-volatile store (not shown) for execution bymicroprocessor 238. Such flexibility in application installationincreases the functionality of mobile station 200 and may provideenhanced on-device functions, communication-related functions, or both.For example, secure communication applications may enable electroniccommerce functions and other such financial transactions to be performedusing mobile station 200.

In a data communication mode, a received signal such as a text messageor web page download will be processed by communication subsystem 211and input to microprocessor 238. Microprocessor 238 will preferablyfurther process the signal for output to display 222 or alternatively toauxiliary I/O device 228. A user of mobile station 200 may also composedata items, such as e-mail messages or short message service (SMS)messages, for example, using keyboard 232 in conjunction with display222 and possibly auxiliary I/O device 228. Keyboard 232 is preferably acomplete alphanumeric keyboard and/or telephone-type keypad. Thesecomposed items may be transmitted over a communication network throughcommunication subsystem 211.

For voice communications, the overall operation of mobile station 200 issubstantially similar, except that the received signals would be outputto speaker 234 and signals for transmission would be generated bymicrophone 236. Alternative voice or audio I/O subsystems, such as avoice message recording subsystem, may also be implemented on mobilestation 200. Although voice or audio signal output is preferablyaccomplished primarily through speaker 234, display 222 may also be usedto provide an indication of the identity of a calling party, duration ofa voice call, or other voice call related information, as some examples.

Serial port 230 in FIG. 2 is normally implemented in a personal digitalassistant (PDA)-type communication device for which synchronization witha user's desktop computer is a desirable, albeit optional, component.Serial port 230 enables a user to set preferences through an externaldevice or software application and extends the capabilities of mobilestation 200 by providing for information or software downloads to mobilestation 200 other than through a wireless communication network. Thealternate download path may, for example, be used to load an encryptionkey onto mobile station 200 through a direct and thus reliable andtrusted connection to thereby provide secure device communication.

Short-range communications subsystem 240 of FIG. 2 is an additionaloptional component which provides for communication between mobilestation 200 and different systems or devices, which need not necessarilybe similar devices. For example, subsystem 240 may include an infrareddevice and associated circuits and components, or a Bluetooth™communication module to provide for communication with similarly-enabledsystems and devices. Bluetooth™ is a registered trademark of BluetoothSIG, Inc.

Mobile station 200 also includes a battery interface 254 for receivingone or more rechargeable batteries 256. When mobile station 200 ispowered on by the end user (at keyboard 232, for example), battery 256provides electrical power to most if not all electrical circuitry inmobile station 200. Battery interface 254 provides for both a mechanicaland electrical connection for battery 256. Battery interface 254 iscoupled to a regulator (not shown in FIG. 2) which regulates power toall of the circuitry. When mobile station 200 is powered off by the enduser to place mobile station 200 in a power-off state, electrical powerto most circuits (e.g. at least to communication sub-system 211) is cutoff.

FIG. 3 shows a particular system structure for communicating with awireless communication device. In particular, FIG. 3 shows basiccomponents of an IP-based wireless data network, such as a GPRS network.Mobile station 200 communicates with a wireless packet data network 345,and may also be capable of communicating with a wireless voice network(not shown). The voice network may be associated with IP-based wirelessnetwork 345 similar to, for example, GSM and GPRS networks, oralternatively may be a completely separate network. The GPRS IP-baseddata network is unique in that it is effectively an overlay on the GSMvoice network. As such, GPRS components will either extend existing GSMcomponents, such as base stations 320, or require additional componentsto be added, such as an advanced Gateway GPRS Service Node (GGSN) as anetwork entry point 305.

As shown in FIG. 3, a gateway 340 may be coupled to an internal orexternal address resolution component 335 and one or more network entrypoints 305. Data packets are transmitted from gateway 340, which issource of information to be transmitted to mobile station 200, throughnetwork 345 by setting up a wireless network tunnel 325 from gateway 340to mobile station 200. In order to create this wireless tunnel 325, aunique network address is associated with mobile station 200. In anIP-based wireless network, however, network addresses are typically notpermanently assigned to a particular mobile station 200 but instead aredynamically allocated on an as-needed basis. It is thus preferable formobile station 200 to acquire a network address and for gateway 340 todetermine this address so as to establish wireless tunnel 325.

Network entry point 305 is generally used to multiplex and demultiplexamongst many gateways, corporate servers, and bulk connections such asthe Internet, for example. There are normally very few of these networkentry points 305, since they are also intended to centralize externallyavailable wireless network services. Network entry points 305 often usesome form of an address resolution component 335 that assists in addressassignment and lookup between gateways and mobile devices. In thisexample, address resolution component 335 is shown as a dynamic hostconfiguration protocol (DHCP) as one method for providing an addressresolution mechanism.

A central internal component of wireless data network 345 is a networkrouter 315. Normally, network routers 315 are proprietary to theparticular network, but they could alternatively be constructed fromstandard commercially available hardware. The purpose of network routers315 is to centralize thousands of base stations 320 normally implementedin a relatively large network into a central location for a long-haulconnection back to network entry point 305. In some networks there maybe multiple tiers of network routers 315 and cases where there aremaster and slave network routers 315, but in all such cases thefunctions are similar. Often network router 315 will access a nameserver 307, in this case shown as a dynamic name server (DNS) 307 asused in the Internet, to look up destinations for routing data messages.Base stations 320, as described above, provide wireless links to mobiledevices such as mobile station 200.

Wireless network tunnels such as a wireless tunnel 325 are opened acrosswireless network 345 in order to allocate necessary memory, routing, andaddress resources to deliver IP packets. In GPRS, such tunnels 325 areestablished as part of what are referred to as “PDP contexts” (i.e. datasessions). To open wireless tunnel 325, mobile station 200 must use aspecific technique associated with wireless network 345. The step ofopening such a wireless tunnel 325 may require mobile station 200 toindicate the domain, or network entry point 305 with which it wishes toopen wireless tunnel 325. In this example, the tunnel first reachesnetwork router 315 which uses name server 307 to determine which networkentry point 305 matches the domain provided. Multiple wireless tunnelscan be opened from one mobile station 200 for redundancy, or to accessdifferent gateways and services on the network. Once the domain name isfound, the tunnel is then extended to network entry point 305 andnecessary resources are allocated at each of the nodes along the way.Network entry point 305 then uses the address resolution (or DHCP 335)component to allocate an IP address for mobile station 200. When an IPaddress has been allocated to mobile station 200 and communicated togateway 340, information can then be forwarded from gateway 340 tomobile station 200.

Wireless tunnel 325 typically has a limited life, depending on mobiledevice's 100 coverage profile and activity. Wireless network 345 willtear down wireless tunnel 325 after a certain period of inactivity orout-of-coverage period, in order to recapture resources held by thiswireless tunnel 325 for other users. The main reason for this is toreclaim the IP address temporarily reserved for mobile station 200 whenwireless tunnel 325 was first opened. Once the IP address is lost andwireless tunnel 325 is torn down, gateway 340 loses all ability toinitiate IP data packets to mobile station 200, whether overTransmission Control Protocol (TCP) or over User Datagram Protocol(UDP).

In this application, an “IP-based wireless network” (one specific typeof wireless communication network) may include but is not limited to:(1) a Code Division Multiple Access (CDMA) network that has beendeveloped and operated by Qualcomm; (2) a General Packet Radio Service(GPRS) network for use in conjunction with Global System for MobileCommunications (GSM) network both developed by standards committee ofEuropean Conference of Postal and Telecommunications Administrations(CEPT); and (3) future third-generation (3G) networks like Enhanced Datarates for GSM Evolution (EDGE) and Universal Mobile TelecommunicationsSystem (UMTS). It is to be understood that although particular IP-basedwireless networks have been described, the communicationre-establishment schemes of the present application could be utilized inany suitable type of wireless packet data network.

The infrastructure shown and described in relation to FIG. 3 may berepresentative of each one of a number of different communicationnetworks which are provided and available in the same geographic region.One of these communication networks will be selected by the mobiledevice, either in an automatic or manual fashion, for communications.

FIG. 4 is an illustration of mobile station 200 currently registered andcommunicating with a non-home communication network 406. A homecommunication network 402 of mobile station 200 is nearby and includesat least one base station 404 which has a signal coverage area which ispartially designated by a dashed line 405. Home network 402 isassociated with a first Mobile Country Code (MCC)/Mobile Network Code(MNC) pair. Non-home network 406 also includes at least one base station408 which has a signal coverage area which is partially designated by adashed line 409. Non-home network 406 is associated with a secondMCC/MNC pair. The MCCs and MNCs are codes that are broadcasted bynetworks and received by mobile stations 200 during scanning operationsof the mobile stations.

Consider the situation where mobile station 200 is being initiallyserved by non-home communication network 406 and subsequentlyexperiences an out-of-coverage condition. Per the specifications, afterrecovering from the out-of-coverage condition, mobile station 200 mustoperate to select the PLMN with which it had just previously registered(i.e. its “RPLMN”). In FIG. 4, this would be non-home network 406. Ifthe RPLMN is unavailable, mobile station 200 performs a scan to identifyand select a different PLMN (which may be its HPLMN). However, thecurrent specifications-do not clearly and specifically address thesituation where the RPLMN is not the HPLMN of mobile station 200. If theRPLMN is not the HPLMN, but the HPLMN (e.g. home network 402 of FIG. 4)is available after the recovery from the out-of-coverage condition,mobile station 200 is restricted to selecting the non-home RPLMN (ifavailable) upon recovery. This situation is depicted in FIG. 4 where thesignal coverage areas of both networks are overlapping. Similar problemsexist when the mobile station is powered off while operating with theRPLMN and subsequently powered back on. Such conventional operation isdescribed in ETSI specs 3.22/23.122.

FIG. 5 is a flowchart for generally describing the method of selecting acommunication network according to current standards, which is describedin more detail in current ETSI specs 3.22/23.122. Beginning at a startblock 502, a mobile station operates on a non-home communication network(step 504) (e.g. non-home network 406 of FIG. 4). The non-home networkis not the home network of the mobile station; the home network has afirst MCC/MNC pair and the non-home network has a second MCC/MNC pairdifferent from the first MCC/MNC pair. If the mobile station experiencesan out-of-coverage condition (step 506), the mobile station waits toregain signal coverage (step 508). Alternatively, if the mobile stationis powered off by the end user (step 506), it waits for a user inputsignal to be powered back on (step 508). If and when the mobile stationregains network signal coverage, or is powered back on, the mobilestation performs a scanning operation to identify all available networkswithin its coverage area (step 510). The available networks may or maynot include the home network of the mobile station (e.g. home network402 of FIG. 4). Per the current standards, the mobile station must thenidentify whether the previous network (e.g. non-home network 406) isidentified by the scanning operation (step 512). The previous networkmay be referred to as the “Registered PLMN” or RPLMN. If the previousnetwork is available at step 512, the mobile station must select andoperate with the previous network. This is true even if the HPLMN isavailable at that time. If the previous network is unavailable at step512, the mobile station selects the best network using network selectiontechniques (e.g. based on a prioritized network list) (step 516).Similar problems exist when the mobile station is powered off whileoperating with the RPLMN and subsequently powered back on.

FIG. 6 is a flowchart for describing a method for “automatic” selectionof a communication network with home network prioritization afternetwork signal recovery and/or power-on of the present application. Sucha method may be employed in connection with devices shown and describedabove in relation to FIGS. 1-4. For example, the steps may be performedby microprocessor 238 and communication subsystem 211 of FIG. 2.

Beginning at a start block 602 of FIG. 6, a mobile station registers andoperates with a non-home communication network (step 604) (e.g. non-homenetwork 406 of FIG. 4). The non-home network is not the home network ofthe mobile station; the home network has a first MCC/MNC pair and thenon-home network has a second MCC/MNC pair different from the firstMCC/MNC pair. If the mobile station experiences an out-of-coveragecondition with the network (step 606), the mobile station waits toregain signal coverage (step 608). Alternatively, if the mobile stationis powered off by the end user (step 606), it waits for a user inputsignal to be powered back on (step 608). If and when the mobile stationregains network signal coverage, or is powered back on, the mobilestation performs a scanning operation to identify all available networkswithin its coverage area (step 610). The available networks may or maynot include the home network of the mobile station (e.g. home network402 of FIG. 4).

In the present application, the mobile station then identifies whetherthe home network is available as indicated from the scanning operation(step 612). If the home network (e.g. home network 402 of FIG. 4) isavailable, the mobile station selects and registers with the homenetwork for operation (step 614). Thus, the home network is given firstpriority. If the home network is unavailable at step 612, the mobilestation identifies whether the previous network (e.g. non-home network406) is available as indicated from the scanning operation (step 616).The previous network may be referred to as the “Registered PLMN” orRPLMN. If the previous network is available at step 616, the mobilestation continues operating with the previous network (step 618). If theprevious network is unavailable at step 616, the mobile station selects,registers, and operates with the next “best” network using networkselection techniques (e.g. based on a prioritized network list) (step620).

Thus, the above method provides a solution to a problem that thespecifications do not clearly and specifically address: the situationwhere the RPLMN is not the HPLMN of the mobile station. If the RPLMN isnot the HPLMN, and the HPLMN is available after the recovery from theout-of-coverage condition or after power-on, the standards specify thatthe mobile station is limited to selecting the non-home RPLMN (ifavailable).

FIG. 7 is a flowchart for describing a method for “manual” selection ofa communication network with home network prioritization after networksignal recovery and/or power on of the present application. Such amethod may be employed in connection with devices shown and describedabove in relation to FIGS. 1-4. For example, the steps may be performedby microprocessor 238 and communication subsystem 211 of FIG. 2. Thismethod is preferably performed in the same device that performs themethod of FIG. 6.

Beginning at a start block 702 of FIG. 7, a mobile station operates on anon-home communication network after an end-user manual selection of thenon-home communication network (e.g. non-home network 406 of FIG. 4)through the user interface (step 704). The non-home network is not thehome network of the mobile station; the home network has a first MCC/MNCpair and the non-home network has a second MCC/MNC pair different fromthe first MCC/MNC pair. If the mobile station experiences anout-of-coverage condition with the network (step 706), the mobilestation waits to regain signal coverage (step 708). Alternatively, ifthe mobile station is powered off by the end user (step 706), it waitsfor a user input signal to be powered back on (step 708). If and whenthe mobile station regains network signal coverage, or is powered backon, the mobile station performs a scanning operation to identify allavailable networks within its coverage area (step 710). The availablenetworks may or may not include the home network of the mobile station(e.g. home network 402 of FIG. 4).

The mobile station identifies whether the previous manually-selectednon-home network (e.g. non-home network 406 of FIG. 4) is available asindicated from the scanning operation (step 712). This previous networkmay be referred to as the “Registered PLMN” or RPLMN. If the previousmanually-selected non-home network is available at step 712, the mobilestation identifies whether the home network (e.g. home network 402 ofFIG. 4) is available as indicated from the scanning operation (step714). If the home network is unavailable at step 714, then the mobilestation continues operating with the previous manually-selected non-homenetwork (step 716).

If the home network is available as identified in step 714, then themobile station causes a visual input prompt to be displayed in itsvisual display for manual selection of the home network by the end user(step 718). For example, the visual input prompt may read “SELECT HOMENETWORK? YES or NO”. The mobile station may further cause the soundingof an audible alert from the user interface. If the end user manuallyselects the home network in step 718 (“Yes”), then the mobile stationregisters and operates with the home network (step 720). If no userinput is received but rather an expiration of a predetermined timeperiod occurs at step 718 (“Time Out”), or the end user does not wish toutilize the home network at step 718 (“No”), then the mobile stationselects, registers, and operates with the previous manually-selectednon-home network (step 716).

If the previous manually-selected non-home network is unavailable atstep 712, the mobile station identifies whether the home network (e.g.home network 402 of FIG. 4) is available as indicated from the scanningoperation (step 722). If the home network is available as identified instep 722, then the mobile station causes a visual input prompt to bedisplayed in its visual display for manual selection of the home networkby the end user (step 724). For example, the visual input prompt mayread “SELECT HOME NETWORK? YES or NO”. The mobile station may furthercause the sounding of an audible alert from the user interface. If theend user manually selects the home network in step 724 (“Yes”), then themobile station registers and operates with the home network (step 726).If no user input is received but rather an expiration of a predeterminedtime period occurs in step 724 (“Time Out”), then the mobile stationselects, registers, and operates with the home network (step 726).

If the home network is unavailable as identified back in step 722, thenthe mobile station causes the list of all available networks to bedisplayed for manual selection by the end user (step 728). If the enduser manually selects a network in the displayed list of all availablenetworks at step 728 (“Selection”), then the mobile station registersand operates with the manually selected network (step 730). If no userinput is received but rather an expiration of a predetermined timeperiod occurs in step 728 (“Time Out”), then the mobile station selects,registers, and operates with any network which provides only emergencyservice (i.e. no service—including voice and data communicationservice—other than emergency service such as “911” calls) (step 732).

Advantageously in FIG. 7, even in a manual selection mode where choicesare made by the end user, the mobile station makes the end user aware ofrecent availability of the home network in a timely and unobtrusivefashion. Overall, the mobile station helps facilitate the selection ofthe best network for the end user even in the manual selection mode.

Final Comments. Network selection methods and apparatus with homenetwork prioritization after network signal recovery and/or power onhave been described. In one illustrative example involving automaticnetwork selection, a mobile station selects and operates with a non-homecommunication network. The mobile station then experiences anout-of-coverage condition (or a power down condition) but subsequentlyregains signal coverage (or is powered back on). In response, the mobilestation scans to identify a plurality of communication networks in itscoverage area. If a home communication network (e.g. HPLMN) isidentified as being available, the mobile station selects and operateswith the home communication network. Otherwise, if the previous non-homecommunication network (e.g. RPLMN) is identified as being available, themobile station continues operation with the previous non-homecommunication network.

A mobile station having an “automatic” network selection technique ofthe present application includes a wireless transceiver, an antennacoupled to the wireless transceiver, and one or more processors coupledto the wireless transceiver. The one or more processors are configuredto select a communication network with which to communicate by selectingand operating with a communication network and, after regaining signalcoverage from an out-of-coverage condition with the communicationnetwork, or after powering on from a power-off state, causing thefollowing acts to be performed: scanning to identify a plurality ofcommunication networks in a coverage area within which the mobilestation is operating; if a home communication network of the mobilestation is identified as being available by the scanning, selecting andoperating with the home communication network; and otherwise, if thecommunication network is identified as being available by the scanning,continuing operation with the communication network.

A communication system having an “automatic” network selection techniqueof the present application includes a first communication network, asecond communication network, and one or more mobile stations which areoperable with the first and the second communication networks. The oneor more mobile stations have the second communication network designatedas a home communication network. The one or more mobile stations areoperative for selecting and operating with the first communicationnetwork and, after regaining signal coverage from an out-of-coveragecondition with the first communication network, or powering on from apower-off state, causing the following acts to be performed: scanning toidentify a plurality of communication networks in a coverage area withinwhich the mobile station is operating; if the home communication networkof the mobile station is identified as being available by the scanning,selecting and operating with the home communication network; andotherwise, if the first communication network is identified as beingavailable by the scanning, continuing operation with the communicationnetwork.

In a manual network selection mode, a user input from a user interfacefor manually selecting a communication network with which the mobilestation will operate is received. After regaining network signalcoverage from an out-of-coverage condition, or after powering on from apower-off state, the mobile station scans to identify a plurality ofcommunication networks in a coverage area. If the previousmanually-selected network (e.g. the RPLMN) is available but the homenetwork is unavailable as identified by the scanning, then the mobilestation continues to operate with the previous manually-selectednetwork. If a home communication network (e.g. HPLMN) is identified asbeing available by the scanning, however, the mobile station causes avisual input prompt to be displayed for manual selection of the homenetwork.

A mobile station having a “manual” network selection technique of thepresent application includes a user interface, a wireless transceiver,an antenna coupled to the wireless transceiver, and one or moreprocessors coupled to the wireless transceiver. The one or moreprocessors being configured to provide for the selection of acommunication network by receiving a user input from the user interfacefor manually selecting a communication network for the mobile station;selecting and operating with the manually-selected communication networkin response to the user input; and after regaining signal coverage froman out-of-coverage condition with the manually-selected communicationnetwork, or after power-on from a power-off state, causing the followingacts to be performed: scanning to identify a plurality of communicationnetworks in a coverage area within which the mobile station isoperating; if, as identified from the scanning, the communicationnetwork is available but a home communication network is unavailable:continuing operations with the communication network; and if, asidentified from the scanning, a home communication network of the mobilestation is available: causing a visual input prompt to be displayed formanually selecting the home communication network.

A communication system having a “manual” network selection technique ofthe present application includes a first communication network, a secondcommunication network, and one or more mobile stations which areoperable with the first and the second communication networks. The oneor more mobile stations have the second communication network designatedas a home communication network. The one or more mobile stations areoperative for receiving a user input from a user interface of the mobilestation for manually selecting the first communication network foroperation; selecting and operating with the first communication networkin response to the user input; and after regaining signal coverage froman out-of-coverage condition with the first communication network, orafter a power-on from a power-off state, causing the following acts tobe performed: scanning to identify a plurality of communication networksin a coverage area within which the mobile station is operating; if, asidentified from the scanning, the communication network is available butthe second communication network is unavailable: continuing operationswith the first communication network; and if, as identified from thescanning, the second communication network of the mobile station isavailable: causing a visual input prompt to be displayed for manuallyselecting the second communication network.

The above-described embodiments of invention are intended to be examplesonly. Alterations, modifications, and variations may be effected toparticular embodiments by those of skill in art without departing fromscope of invention, which is defined solely by claims appended hereto.

1. A network selection method for a mobile station, comprising:selecting and operating with a non-home communication network; afterregaining signal coverage from an out-of-coverage condition, performingthe following acts of: identifying a plurality of communication networksin a coverage area within which the mobile station is operating; if ahome communication network is identified as being available, selectingand operating with the home communication network; and otherwise, if thenon-home communication network is identified as being available,selecting and operating with the non-home communication network.
 2. Themethod of claim 1, further comprising: otherwise, if the non-homecommunication network is identified as being unavailable, selecting andoperating with an alternate communication network based on a list ofnetworks.
 3. The method of claim 1, further comprising: otherwise, ifthe non-home communication network is identified as being unavailable,receiving a selecting of an alternate communication network.
 4. Themethod of claim 1, further comprising: otherwise, if the non-homecommunication network is identified as being unavailable, presenting aselection of at least one available alternate communication networks. 5.The method of claim 1, further comprising: otherwise if no homecommunication networks are identified and no manual selection hasoccurred: selecting and operating with an alternate network whichprovides only emergency services.
 6. A mobile station, comprising: awireless transceiver; an antenna coupled to the wireless transceiver;one or more processors coupled to the wireless transceiver; the one ormore processors being configured to select a communication network withwhich to communicate, the mobile station configured to: select andoperate with a non-home communication network; and after regainingsignal coverage from an out-of-coverage condition, the mobile stationfurther configured to: identify a plurality of communication networks ina coverage area within which the mobile station is operating; if a homecommunication network is identified as being available, select andoperate with the home communication network; and otherwise, if thenon-home communication network is identified as being available, selectand operate with the non-home communication network.
 7. The mobilestation of claim 6, further configured to: otherwise, if the non-homecommunication network is identified as being unavailable, select andoperate with an alternate communication network based on a list ofnetworks.
 8. The mobile station of claim 6, further configured to:otherwise, if the non-home communication network is identified as beingunavailable, receive a selecting of an alternate communication network.9. The mobile station of claim 6, further configured to: otherwise, ifthe non-home communication network is identified as being unavailable,present a selection of at least one available alternate communicationnetworks.
 10. The mobile station of claim 6, further configured to:otherwise if no home communication networks are identified and no manualselection has occurred: select and operate with an alternate networkwhich provides only emergency services.
 11. A communication system,comprising: a first non-home communication network; a secondcommunication network; one or more mobile stations which are operablewith the first non-home communication network and the secondcommunication network; the one or more mobile stations having the secondcommunication network designated as a home communication network; theone or more mobile stations being operative to perform a networkselection method comprising: selecting and operating with a non-homecommunication network; after regaining signal coverage from anout-of-coverage condition, performing the following acts of: identifyinga plurality of communication networks in a coverage area within whichthe mobile station is operating; if a home communication network isidentified as being available, selecting and operating with the homecommunication network; and otherwise, if the non-home communicationnetwork is identified as being available, selecting and operating withthe non-home communication network.
 12. The communication system ofclaim 11, further comprising: otherwise, if the non-home communicationnetwork is identified as being unavailable, selecting and operating withan alternate communication network based on a list of networks.
 13. Thecommunication system of claim 11, further comprising: otherwise, if thenon-home communication network is identified as being unavailable,receiving a selecting of an alternate communication network.
 14. Thecommunication system of claim 11, further comprising: otherwise, if thenon-home communication network is identified as being unavailable,presenting a selection of at least one available alternate communicationnetworks.
 15. The communication system of claim 11, further comprising:otherwise if no home communication networks are identified and no manualselection has occurred: selecting and operating with an alternatenetwork which provides only emergency services.